<!DOCTYPE html>
<html>
<head>
  <meta charset="utf-8">
  <title>jquery.scrolltotop.js插件DEMO</title>
  <style>
  .content{height: 3000px; background: yellow;}
  </style>
</head>
<body>

  <p class="content">
    很高很高的内容
  </p>

  <script src="jquery-1.11.3.js"></script>
  <script src="../jquery.scrolltotop.js"></script>
  <script>
  window.onload = function(){
    scrolltotop.init();
  };
  </script>
</body>
</html>